SlowedAndReverb.Studio by Alex Bainter

Make Slowed+Reverb, Daycore, Nightcore, and Sped Up remixes of your favorite songs with the SlowedAndReverb.Studio browser extension. No need to download files or learn complicated audio editing software—just click the extension and adjust the speed and reverb however you like, or use one of the included presets!

This extension was primarily made for YouTube, but will also work on many other websites that play audio or video. Please understand that some sites aren't compatible yet, but this may improve with future releases of the extension.

Upgrade to Pro to boost bass, make custom presets, set your own default settings, keep the original pitch for all speeds, and to enable fine-tunable controls to get your remix just right.